The aims of the study are identify the histopathological defects in the tilted mouse using light and transmission electron microscopy. Characterize the functional deficits in these mice with behavioral tests, (2) identify and sequence proteins that are expressed in the vestibular sensory epithelium, vestibular endolymph and otoconial membranes by identifying those proteins that are missing or defective in the tilted mouse. Clone cDNAs specifically expressed in the vestibular system, (3) determine where the genes are expressed and whether they are mutated in the tilted mouse and in other related mouse mutants with otoconial pathology. Use these genes to study molecular mechanisms regulating vestibular system development and pathology Mass spectrometry is used for molecular weight and sequencing of proteins.